Compendium of All Natural Science

those things which happen very rarely are called improper causes. For those things which occur frequently happen either by nature or by the activity of the mind. Those things, however, which happen neither frequently nor rarely, are not subject to the power of fortune: but are found only in those things which are bound to no specific thing. For example, matter can be both hot and cold of itself; but if it be assigned to some necessary cause, it is impossible for either of the two to happen equally.

16. On monsters.

Just as certain efficient causes are improper, so also effects are found which have been accustomed to be called monstrous. And these, although they do not occur according to the intent of particular causes, are nevertheless bestowed by universal nature, not without a certain reason.

17. On the order of causes, and the sequence of effects according to the four kinds of causes.

There is, moreover, a certain order among causes, and indeed a most necessary one. For the form constrains the subject matter, the efficient cause the form, and the end the efficient cause. Therefore, the end is the most excellent among all causes. For this reason, philosophers have also most excellently noted that, just as conclusions are said to follow from premises, so from the end must those things which are directed toward it be concluded. But some things have also been observed,